The present invention relates to aircraft seat structures and more particularly to protective seats that reposition the body of an occupant to improve G-load tolerance during high acceleration flight.
High performance aircraft subject the pilot to high accelerations or G-loads both in the direction of the flight path and along the vertical or Z-axis of the aircraft during curved flight trajectories, such as in sharp turns and steep dive recoveries. These latter radial G-loads, which tend to drain blood away from the brain and toward the lower extremities of the normally erect pilot, have increased in magnitude and frequency with improvements in aircraft structural stength, maneuverability, and power so that as a consequence, the ability of the pilot to withstand the load forces over a sustained period is generally below the performance capabilities of the aircraft. In particular, current combat aircraft possess power and maneuvering capabilities that severely test the pilots G-load tolerance, and as a result, the risks of pilot fatigue, grayout (tunnel vision), and blackout (loss of consciousness) have been significantly increased.
Various approaches have been taken to increase the G-load tolerance of the pilot and other crew members of such high performance aircraft. The use of extensive high-G training (physiological straining and muscular control) and anti-G suits have been found to offer some improvement but cannot match the aircraft capabilities without compromising the pilot's ability to effectively discern, command, and control his aircraft. Substantial improvement in pilot G-load tolerance and performance have been achieved using supinating seats that reposition the pilot from a normally upright position to an extended, reclined posture during high-acceleration maneuvers so that the pilot's retinal-aortic line is more favorably positioned substantially perpendicular to the radial G-load vector. Supinating seats of this type generally include articulated seat and back supporting members that forwardly elevate the lower torso of the pilot without substantially affecting the position of his head. While such supinating seats having extended the pilot's ability to withstand radial G-loads, there remains a need to increase both the level and duration of pilot tolerance to radial G-load exposure so as to match the performance capabilities of developing high performance aircraft. Furthermore, problems of conserving cockpit geometry and maintaining safe conditions for ejection have confronted aircraft developers in accommodating existing supination schemes because of their general feature of substantial pilot elongation requiring forward invasion of the instrument panel for leg clearance.